In:
Electronics, MDPI AG, Vol. 12, No. 8 ( 2023-04-07), p. 1767-
Kurzfassung:
Non-recessed ohmic contact resistance (Rc) on ultrathin-barrier (UTB) AlGaN( 〈 6 nm)/GaN heterostructure was effectively reduced to a low value of 0.16 Ω·mm. The method called the ‘ohmic-before-passivation’ process was adopted to eliminate the effects of fluorine plasma etching, in which an alloyed Ti/Al/Ni/Au ohmic metal stack was formed prior to passivation. The recovery of 2-D Electron Gas (2DEG) adjacent to the ohmic contact was enhanced by composite double-layer dielectric with AlN/SiNx passivation. It is found that the separation between the recovered 2DEG and the ohmic contacting edge can be remarkably reduced, contributing to a reduced transfer length (LT) and low Rc, as compared to that of ohmic contact to the AlGaN(~20 nm)/GaN heterostructure with a pre-ohmic recess process. Thermionic field emission is verified to be the dominant ohmic contact mechanism by temperature-dependent current-voltage measurements. The low on-resistance of 3.9 Ω·mm and the maximum current density of 750 mA/mm with Vg = 3 V were achieved on the devices with the optimized ohmic contact. The non-recessed ohmic contact with the ‘ohmic-before-passivation’ process is a promising strategy to optimize the performance of low-voltage GaN-based power devices.
Materialart:
Online-Ressource
ISSN:
2079-9292
DOI:
10.3390/electronics12081767
Sprache:
Englisch
Verlag:
MDPI AG
Publikationsdatum:
2023
ZDB Id:
2662127-7
